Beschreibung:
Silicon (Si) plays an essential role in the biogeochemistry of rivers. Despite decades of research, how damming, eutrophication and climate change alters the DSi abundance and flux is still poorly characterized. Here, we explore the long-term changes in Si transport by the Changjiang (Yangtze) River through long-term observations. The results showed that Three Gorges Reservoir (TGR) could enhance DSi transfer only during low-flow time periods, and a downstream DSi retention effect by the TGR was found between the Yichang and Jianli stations in the Changjiang River. This resulted in a DSi loss during March and April in the mainstream from Three Gorges Dam to Jianli but a DSi addition during July and October along the main channel of the Changjiang River. Long-term data showed a sharp decrease in DSi abundance at the Cuntan, Hankou and Datong stations between the 1960s and 1980s, but a slight increase in DSi between the 1990s and 2010s at these stations. The decrease in DSi during the 1960s -1980s was primarily the result of a decrease trend of silicate weathering, while a slight DSi increase compared to the temperature/DSi relation after the 1990s was largely due to increased DSi retention in the basin by damming and eutrophication. Eutrophication and damming that increases silicate trapping in both the river channel and reservoir systems in the low-flow period and thus enhances the nutrient distortion in the coastal ocean is a global problem in many watersheds with intensive anthropogenic disturbance